Power transmission



Dec- 6, 1949 A. J. sYRovY ETAL 2,490,604

PUWER TRANSMISS ION Filed May 3l, 1945 6 Shee'ts-Sheet 1 POWER TRANSMISSION 6 Sheets-Sheet 2 Filed May 51. 1945 Dec. 6, 1949 A. J. SYROVY ET AL POWER TRANSMISSION Filed May 3l. 1945 6 Sheets-Sheet 3 INVENTOR-S. loira/7 J'efayf, a jdt/ella',

Dec. 6, 1949 A. J. sYRovY ETAL 2,490,604

POWER TRANSMISSION Filed May 3l, 1945 6 Sheets-Sheet 4 Qum- /7 r raro/5K5.

Dec. 6, 1949 A. J. sYRovY ETAL 2,490,604

POWER TRNSMISSIN Filed May s1, 194s e sheets-sheet 5 Dec. 6, 194.9 MJ. sYRow ETAL 2,490,604

POWER TRANSMISSION 6 Sheets-Sheet 6 Filed may 31, 1945 .1b/75's l 4 M ATTORNEY.:

Patented Dee. 6, 1949 2,490,604 POWER TRANSMISSIDN Augustin J. Syrovy and Teno Lavelli,

Mich..

assigner-s to Chrysler Corporation. Highland Park, Mich., a corporation of Delaware Application May 31, 1945. Serial No. 506,842 l Claims. (Cl. 'll-472) This invention relates to power transmissions and refers more particularly to improvements in transmissions of the type adapted to transmit power from the engine to the driving wheels of motor vehicles.

In transmissions of the automatic or semi-automatic types, prior to our invention, servo-motor means of the pressure iluid type has been provided for power manipulative control of speed ratio change. Such servo-motors often employ oil or the equivalent as the operating medium and are known generally as hydraulically" operated transmissions. In arrangements of this type it has been customary to provide a valve for the control of the oil to the servo-motor and usually the valve is itself operated by a motor such as a solenoid which lends itself to convenient control by governor, kickdown switch, dash switch, and other controls. In order to properly control the oil pressure supply to the servomotor and venting the same. it has been deemed necessary as a practical matter to provide porting of generous capacity which in turn requires a relatively long valve stroke of around inch, by way of example. In order to quickly operate the type of valve required over a. relatively long stroke, the solenoid for actuating the valve must be relatively large as it must naturally have sufficient capacity to do the work required. This results in a requirement for relatively high current, complicated wiring control circuit, and relatively high cost.

One object of our invention is to overcome the aforesaid objections by providing a control wherein the power required to operate the valve is largely derived from the pressure of the uid operating medium` Another object is to provide a control in which a very small size solenoid of small current requirement and small stroke in the order of around V8 inch. for example, is so arranged as to control a fluid servo-motor without sacriiicing the deslred generous size valve porting and quick valve operation.

A further object is to provide a control in which the electrical system for controlling the solenoid is of a simplied arrangement being required to carry only a relatively small current.

In carrying out our invention we provide what may be termed a pilot valve of relatively low inertia and small stroke, this pilot valve serving to control iiuid pressure operation of a main valve which may have the desired generous porting and as large a size and stroke as desired withd out penalizing the solenoid. Such arrangement lends itself to quantity manufacture as it is not sensitive to minor variations as is the case where attempts are made to control the porting with a short stroke main valve operated directly from the solenoid. Furthermore, with our arrangelo ment the solenoid is not called upon to overcome sticking of the main valve as is experienced in cold weather.

In order to minimize the work required by the solenoid whereby the solenoid may be very small in size and of very small current requirements. we have provided a pilot valve which is balanced at all times with respect to the pressure of the oil to which it is subjected. In this manner the oil pressure does not operate on the solenoid plunger and the only work required of the solenoid is to move the pilot valve through its very small stroke and to overcome the pressure of a relatively light spring for return of the solenoid and pilot valve parts. A further feature of our invention resides in the provision of a simple and eii'ective arrangement of overcoming any tendency of the pilot valve to stick against operation b y the solenoid. Thus, we have provided a hammer-blow effect between the solenoid operator and the pilot valve by reason of a small gap or clearance between these parts.

An additional object is to provide a pilot valve and main valve system in which both valves are balanced against the oil pressure and wherein both valves are of simplied low oost construction in which ported valve sleeves are not necessary.

Another object is to provide a transmission control system in which the time for affecting downshift is minimized over prior known devices. Contributing to the attainment of this object are our improved arrangement of short stroke balanced pilot valve, rapid venting control operation of the pilot valve for effecting venting control by the main valve. and an improved arrangement for rapid supply and relief of the pressure iluid to and from the servomotor which controls change speed functions of the transmission.

Another object is to provide an improved drive arrangement for the pressure iluid supply pump such that the pump may be readily inspected and serviced if desired, the speed of the pump drive may be varied, and the pump caused to be eiliciently operated in supplying oil at the required pressure even at relatively low vehicle speeds.

Another object of our invention is to provide a simplified and improved control system for a transmission of the step-up and step-down type wherein ratio changes are produced by power shifts under control of the driver and in response to the speed of travel of the motor vehicle.

A further object is to provide an improved transmission operating system for control of positive interengageable drive control elements such that tendency of the parts to bind or fail to operate is obviated.

Further objects and advantages of our invention will be more apparent from the following description of a typical embodiment. reference being had to the accompanying drawings. in which:

Fig. i is a diagrammatic plan view of the driving power plant for the vehicle.

Fig. 2 is a sectional plan view through the transmission.

Fig. 3 is a transverse sectional elevational view taken longitudinally through the transmission.

Fig. 4 is a detail sectional elevational view illustrating the reverse idler gear.

Fig. 5 is a sectional elevational view through the pump driving mechanism, the view being taken as illustrated by line 5-5 of Fig. 3.

Fig. 6 is a detail view of the servo-motor as seen in Fig. 2 but illustrating the clutch sleeve in its clutched position and the servo-motor vented and in an intermediate position of its clutch releasing operation.

Fig. 'l is a partial development plan view of the automatic clutch sleeve and associated blocker controlled clutching parts, the sleeve being shown in fully released position and the blocker leading the sleeve.

Fig. 8 is a similar view illustrating the sleeve in drive blocked position.

Fig. 9 is a similar view illustrating the clutch sleeve fully clutched with the driving gear.

Fig. 10 is a similar view illustrating the sleeve in fully released position with the blocker lagging the sleeve.

Fig. 1l is a similar view illustrating the blocker in coast blocking relationship relative to the sleeve.

Fig. 12 is a view of the Fig. 6 servo-motor with the parts including the clutch sleeve in fully released position and illustrating diagrammatlcally the pumping and valvlng system.

Fig. 13 is a similar view illustrating the servomotor operated by fluid pressure and the sleeve in the Fig. 8 drive blocked position.

Fig. 14 is an electrical control diagram oi' the transmission.

Fig. i5 is a similar view of a modified control system.

Fig. 16 is an enlarged sectional view of a servomotor piston of modified construction.

In the drawings, Fig. 1 illustrates a typical motor vehicle power plant having a conventional engine A transmitting power through a hydraulic coupling and clutch assembly B of conventional arrangement, the drive then passing through transmission C to the rear vehicle ground wheels 20.

The transmission C comprises an input or driving shaft 2| which receives drive from engine A by way of the clutch assembly B, and an output or driven shaft 22 which is adapted to transmit drive to the vehicle ground wheels 20. The driving shaft 2i carries the main driving gear or pinion 23 and a set of positive jaw-type clutch teeth carried by an automatic clutch sleeve D. The teeth of sleeve D are alternately cut back to provide in effect relatively long teeth 25 and short teeth 26, alternate adjacent pairs being bridged together as shown in Fig. 7.

Sleeve D is slidably splined at its non-bridged teeth 25, 26 on the axially fixed teeth 21 of a hub 28 carried by .the driven third speed gear 22 which is rotatably jsui-nailed on the driven shaft 22 and adapted to be clutched thereto. The forward shift of sleeve D for clutching with teeth 2l is controlled by a blocker E whereby such clutching is limited to synchronous relationship in the speeds of rotation of gears 22 and 22 and. in the particular transmission illustrated, limited to engine coast conditions. When sleeve D is clutched with teeth 2l, then the gears 22 and 22 are in two-way direct drive relationship for a l to l speed ratio drive therebetween.

Gear 29 is also adapted to be driven from gear 22 at a speed ratio different from l to l and to this end we have shown a countershaft type oneway reduction driving means between these gears. This drive comprises the coaxlally rotatable countershaft gears 30 and 3l respectively in con stant mesh with gears 23 and 29 and having an overrunning clutch F operably interposed therein. A stationarily mounted shaft 32 provides a journal support for the countershaft. gears. Assuming the usual clockwise rotation oi shaft 2i, as viewed when looking from front to rear of Fig. 3, then overrunning clutch F will automatically clutch gears 3Ii and 3i together when gear 20 is driven counterclockwise at a speed tending to exceed that of gear 3i and automatically release the drive between these gears to allow gear 22 to freely slow down below the speed of gear 3i.

As thus far described, it will be apparent that with the parts arranged as in Fig. 3, drive of shaft 2| will cause the output gear 29 to be driven at a reduction drive through gears 22, 22, overrunning clutch F, and gear 3l. Should the sleeve D be biased forwardly during this reduction drive, blocker E will obstruct sleeve D in an intermediate position of its shift preventing ratcheting of its teeth with teeth 24. However, if the driver releases the engine throttle control in the form of the usual accelerator pedal then, as will presently be apparent, overrunning clutch F will allow gear 22 to freely coast down relative to the sustained speed of gear 29 and when the speed of gear 23 reaches that of gear 29 blocker E will move to an unblocking position and allow sleeve D to move further forwardly to clutch with teeth 24 under synchronous conditions to provide the direct drive, clutch F continuing its over-running operation. Upon return of sleeve D to its disengaged Fig. 3 position followed by speeding up the engine, overrunning clutch F will tomatically engage to restore the reduction Referring particularly to Figs. 3, and 'l to 1i, blocker E is under constant bias by a spring 22 of very light compression to cause the blocker to frictionally engage the cone portion 34 of gear 22 whereby the blocker attempts to assume the speed of gear 22 within the limits allowed by a lost motion clocking connection with hub 22 provided by the engagement of blocker drive lug 25 in a recess 36 of hub 22. The blocker has blocking teeth 21 engageable with the teeth of sleeve D to perform the blocking function.

In Fig. 'I the sleeve D is in its initial released position of Fig. 3 and the engine is driving gear 22 through the reduction drive thus causing gear 22 to rotate faster than gear 29. Blocker E is frictionally moved to one end of recess 2i, leading the sleeve D.

In Fig. 8 the sleeve is shown biased forwardly to its intermediate blocked position during the Fig. 7 condition of drive through the overrunningclutchF. InFig.8thedrivelug25isin the position of leading the gear 28 as in Fig. 'I because gear 22 is rotating faster than gear 22. Short teeth 22 now engage the blocker teeth 21 thus blocking sleeve D against further forward movement and long teeth 25 are extended between adjacent blocker teeth 21 but there is no ratcheting of the teeth of sleeve D with teeth 24.

aseaeos This is the condition known as drive block or the sleeve D preparatory to clutching sleeve D with teeth 24 and may be maintained as long as desired simply by maintaining the speed oi gear 22 faster than that of gear 22.

Ir now the driver releases the accelerator pedal then the gear 22 will begin to drop in speed and clutch F will overrun allowing gears 2l and 8| to maintain their speeds. As the speed of gear 22 falls on' to approach the speed of gear 2t, blocker D will be finally moved by its friction connection at 34 at the time when gear 22 has dropped to substantially the speed of gear 2l causing the blocker teeth 21 to slide oil the ends of the short teeth 2l whereupon the sustained forward bias on sleeve D causes pairs of the teeth 2l, 26 to move forwardly between the spaces between adjacent blocker teeth 21 and nally to interengage with clutch teeth 24 as shown in Fig. 9. Thus clutching of sleeve D is eifected under blocker control during engine coast from a condition of drive block, such clutching protecting the mechanism against clutching under engine torque and insuring smooth clutching.

Fig. 11 illustrates the condition oi' coast block from which clutching of sleeve D is prevented without first establishing the drive block condition. In Fig. 11 the sleeve D has been biased forwardly from the Fig. l0 Yposition while the gear 23 is rotating at a speed less than that of gear 29. This condition may be experienced where. for example, with the accelerator pedal released for engine idling, the vehicle accelerates from rest down a hill until the vehicle speed or other controlling instrumentality eilects forward bias of sleeve D. Blocker E lags gear 29, the drive lug Il being positioned at the end of recess 2G opposite to that shown in Figs. "l and 8. Now the long teeth 2! engage the blocker teeth 3l holding the sleeve D blocked. If now the engine is accelerated by depressing the accelerator, gear 23 speeds up and in approaching the speed of Rear 29 causes blocker teeth 21 to be rotated clockwise with gear 23 so as to slide off the ends of long teeth 25. Owing to the difference in the lengths of teeth 25 and 26 and because of the rotation of gear 22 faster than gear 29, the sleeve D will not pass through the blocker teeth 31 as the ends of the short teeth 26 will engage the blocker teeth. Thus, in eifect, the blocker teeth .lump the gap between the long and short teeth and the parts become positioned in the Fig. 8 drive block relationship with the engine picking up the reduction drive through the overrunning clutch F. Then if the accelerator pedal is released for the coast. sleeve D will become clutched as illustrated in Fig. 9 as aforesaid.

Transmission C is arranged to provide four forward speeds. neutral, and reverse along with automatic coast step-up at sleeve D from iirst to second, third to fourth, and a reverse step-up. Accelerator pedal kickdown is also provided as a step-down from fourth to third, second to first, and in the reverse.

Countershaft gear Il is a part of a cluster comprising the cam portion 2l for the rollers 38 of overrunning clutch F and a gear 4l. Meshed with gear 4l is a mainshaft ilrst speed gear 42 loose on the shaft 22, the latter carrying splined thereto the reverse driven gear 43. A reverse idler gear ll (Fie. 4) is rotatably iournalled on an idler shaft 4il and is in constant mesh with gear 4l. Flor the reverse drive idler 4I is shifted rearwardly to mesh with gear 4I shown out of its h'ue position in Fis. 4.

Amanuallyshiftabieclutehisslldably splined on a hub 44 iixed to lhaft22 and selectively clutches by shifting clutch G forwardly or rearwardly with teeth 4l or 4l under control of conventional synchroniser blockers 41 and 44 thereby to selectively clutch shaft 22 either with gear 2l or gear 42.

When clutch c+ is shifted forwardly to clutch with teeth 4I of gear 2l, then with sleeve D released as in Fig. 3, there is provided a normal vehicle starting ratio in third speed through parte 22, Il, F, 2i, 20, 4l, G, 44, and 22. If now sleeve D is clutched with teeth 24 as aforesaid, then fourth speed or direct is obtained through parts 22, 24, D, 2l, 2l. 4l, G, 44, and 22. kickdown from fourth to third, leased thereby restoring third by picking up on the overrlxnning clutch F.

When clutch G is shifted rearwardly to clutch with teeth 4l oi' gear 42, then with sleeve D releasedasmrigathereisprovidedamaximum torque multiplying drive in nrst or low through parts 22. 2l, F, 40, 42, 4l, G, 44, and 22. If now sleeve D is clutched with teeth 24 as aforesaid. then second speed is obtained through parts 22. 24, D, 2B, 29, Il. 40, 42, 4l, G, 44, and 22. For the kickdown from second to rst, sleeve D is released thereby restoring first by picking up on the overruning clutch Il'.

For low reverse. idler gear 4| is meshed with gear 43, thus eiecting reverse drive through parts 23, 30, F, 42, 4i, 4l, and 22. 0n coast, step-up of the reverse may be obtained by clutching of sleeve D, the faster reverse drive then passing through parts 23, 24, D, 29, 3|, 40, 4I, 42. and 22. Likewise by release of sleeve D the original low reverse drive may be restored.

As will presently be more apparent, vehicle speed responsive control means is provided for operation of sleeve D so that ilrst, third, and low reverse are free-wheeling in the ordinary sense only below very low car speeds because ordinarily after the car is accelerated in any of these speeds release of the accelerator pedal will en'ect clutching of sleeve D for a two-way drive in second, fourth, or fast reverse almost immediately and as soon as the engine speed drops to synchronize the speed of pinion 22 with that of gear 29. When the car is brought to rest from a transmission setting in second, fourth, or fast drive reverse, or when the accelerator pedal is fully depressed, the automatic step-down or kickdown is effected accompanied by momentary unloading of the torque between the teeth 24 and the teeth of sleeve D thereby providing first, third, or low reverse as the case may be. Because of the uid coupling at B between the engine A and transmission C it is not for the driver to eifect disconnection. as by de-clutching, in the drive between the engine and transmission. Ordinarily such de-clutching is employed at pedal Ell (Fig. l) only in setting the transmission for forward or reverse drive and for shifting to neutral when parking the car.

Usually, forward driving is effected by manually shifting sleeve G forwardly for high range clutching with gear 2l. The car is then accelerated in third with coast step-up to fourth, thence automatically back to third under governor control in stopping or in response to accelerator kickdown when torque multiplication is desired throughthe Btartsandstopsare thus made without le-clutching at pedal Il as l the duid coupling allows the engine to idle with the car at rest.

If desired. the car may be started in first by shifting sleeve G to clutch with gear l2, thence automatically to second for a coast step-up under governor control. On stopping or in response to accelerator kickdown, rst is automatically restored. When in second, a shift of sleeve G forwardly to clutch with gear 20 will provide fourth, skipping third. Also, starting in first followed by forward shift of sleeve G will provide third, skipping second. and fourth is then obtained by the coast step-up.

When sleeve G is maintained in its Fig. 3 neutral position, low reverse is obtained by rearward shift of idler 4I. Step-up of reverse may be effected by coast under governor control followed by restoration of low reverse by stopping the car or by accelerator kickdown.

In order to effect manual shifts of sleeve G any suitable selective shifting means may be employed, prefereably of the type adapted for selective shift control by the car driver at the steering column as, for example, set forth in the patent to O. E. Fishburn No. 2,284,191 of May 26. 1942. This general type of control is well known in the art and forms no part of the present invention and is accordingly disclosed only .in part in the accompanying drawings. Selector operator member El is biased by a spring 52 for engaging the yoke 53 which is mounted on a shift rail 56, the yoke 53 operating in the groove 54 of sleeve G so that by rotating the member 5I by means of a shaft 55 the sleeve G may be shifted forwardly or rearwardly for the high or low forward drive ranges. The operator 5l is depressed by rocking lever 51 for effecting selection of member 5l with the reverse shift rail (not shown) so that by then rotating member 5i the idler ll may be shifted rearwardly by a suitable yoke (not shown) engaged in the idler gear groove 58.

In order to control the shift of sleeve D there is provided a spring and pressure fluid operated serve-motor H comprising a cylinder 62 receiving the fluid operated element or piston 63 having the inner and outer forwardly extending skirts 64 and |15 respectively slidably fitting a rod 66 and cylinder 62. This rod has a rear enlarged portion B1 defining a shoulder '68 engageable with piston 63, the portion 61 being slidably supported in an opening in the rear wall B9 of cylinder 62 and the forward end of rod 66 being slidably supported at its head portion 1li in an opening 1I of the stationarily mounted member 12 which is fixed to the transmission case.

Piston B3 has its outer skirt 65 reduced at 13 adjacent the cammed portions 14, for controlling operation of an ignition control switch J of known type. This switch (Fig. 14) is biased to open position by a spring 16 and has is operating stem engaging a ball 11 so arranged in association with the piston portion 13 that switch J is open when piston 63 is in the Fig. 13 position of forward movement to the end of its pressure fluid operated stroke which is limited by engagement of the piston skirt 65 with the annular member 1li fixed within cylinder l2. When the piston 63 is at the end of its rearward stroke, as in Figs. 2 and 12, at which time the cylinder 62 is vented. then switch J is likewise open as the forward end of the piston skirt is then spaced rearwardly from the ball 11.

The forward end of the piston skirt il one end of the relatively light sleeve spring 19. A shift yoke lil engages the shift groove il of sleeve D and has a mounting head portion 83 secured in fixed relation to the rod it and against which the forward end of spring 19 bears to impart forward bias on sleeve D in response to forward thrust transmitting movement of piston 63. Forward movement of head B3 is limited as in Fig. 6 by the aforesaid member 12. A relatively strong or heavy kickdown spring 84 extends in th space between skirts Il and B5 to seat at its rear end on the piston I3, the forward end of spring M being seated on the abutment member 18. Springs lil and Il are thus concentrically arranged and coaxial with the piston B3 and nested therein.

When oil under pressure is admitted at passage 85 to cylinder 62, piston 63 completes its forward power stroke to its Fig. 13 position serving to compress and further load the kickdown spring B4. At the same time, the engaging spring 1S is further compressed biasing the yoke 8| and hence sleeve D forwardly as Well as rod 66 which moves with yoke 8i and sleeve D. However, sleeve D will be intercepted by blocker E as in Figs. 8 and 13 and will not move to clutch with teeth 24 for one of the aforesaid step-up transmission changes until the engine is allowed to coast from the Fig. 8 drive block condition as aforesaid. Although, during the pressure fluid power stroke of the piston, the cams 14 and 15 cause a momentary closing of the switch J the engine ignition is not interrupted because at such time the ignition grounding line is elsewhere broken as will be presently apparent. When piston B3 is in its forward position of Fig. 13, switch J is open because cam 15 has moved forwardly free of the ball 11 as indicated by the broken line showing in Fig. 14.

The forward stroke of the piston 63 is limited by engagement of the skirt 65 with the member 18. The forward stroke of the collar 33 and sleeve D is less that of piston 63 and is determined by ensagement of the yoke head 83 with the fixed stop 12. The difference in the strokes of the piston and sleeve is such as to open a lost-motion gap BB (Fig. 13) between the forward end of the rod shoulder 68 and piston B3, Fig. 13 illustrating the forwardmost position of shoulder 6l by the broken lines, this gap B8 being suilicient to permit cam 15 to close switch J when the oil pressure is relieved at the cylinder G2 while sleeve iD remains in its clutched position. In this manner the ignition is interrupted for the downshift movement of sleeve D while torque is being transmitted between the teeth 2| and the teeth of the sleeve, the ignition interruption serving to unload the torque sumcient to allow the spring 8l to restore the sleeve D to its Fig. 3 position. Thus when the oil pressure is vented at cylinder $2, bythe kickdown movement of the accelerator pedal or by action of the governor in stopping the car, spring 8| operates lo move piston 63 to take up the lost-motion gap 88, cam 15 closing the switch J to effect ignition interruption and torque unloading at sleeve D. Then. because of the piston 63 engaging the rod shoulder il, rod 16 and yoke 8l move rearwardly as a unit by action of the heavy spring |14, cam 14 serving to restore the ignition by allowing switch J to open just as the sleeve teeth are leaving teeth 24, the rod and yoke along with the piston Il continuing the rearward movement back to the Fig. 12

Y9 position until piston 03 abuts the cylinder head portion 09.

The medium employed to operate the motor H is preferably oil under pressure and the oil in the transmission is preferably employed. This oil is stored in the sump or reservoir 39, a pump K drawing oil by an inlet pipe 90 and chamber passage 90 and delivering oil under pressure to the outlet 9| leading to the gallery 92 closed at one end (Fig. 12) by a spring loaded relief valve 93 arranged to quickly build up the desired pressure in the pressure system served by the pump K and to maintain this pressure, excess oil pressure being relieved by unseating valve 99 until relief or vent passage 94 is exposed to the gallery 92 to an extent determined by the speed of pump K and demand of the system for oil under pressure.

Pump K is preferably driven at a speed proportionate to the speed of travel of the car, as is also a governor L. Both of these devices may be driven from a common gear, if desired, or by separate gears as illustrated. Governor L is shown (Fig. 14) as being driven from a helical gear 95 carried by the countershaft cluster and meshed with the driven gear elements 99 for driving governor L. Inasmuch as for all vehicle drives, the countershaft cluster is drlvingly connected with the driven shaft 22, it will be apparent that the governor is driven at speeds proportionate to the car speed.

. Governor L is provided with a switch M so arranged that it is biased closed until the vehicle is driven up to some predetermined speed, such as around 18 to 20 miles per hour in third for example, at which speed the switch will open. The governor will also open at some lesser speed in accelerating the car from rest in i'irst, depending on the difference in the selected gear ratios of first and third, because in first the countershaft will rotate faster than in third for a given car speed. As will be apparent presently, opening of the governor switch M eil'ects fluid energization of motor H for upshift at sleeve D although the upshift may be delayed under driver control as it is not effected until the driver releases the accelerator pedal to bring about the engine coast. For the downshift operation of sleeve D, governor switch M will close to bring this about when the car slows down to some desired speed usually less than that at which switch M opens due to inherent friction and inertia factors often designed into the governor for desirable overlap in the speeds of functioning to operate switch M. Thus, for example, switch M may close at around l to 12 miles per hour of car speed when in fourth and, of course, at a lesser car speed when the car is brought to rest in second. Sleeve D is also controlled for the downshift independently of closing of governor switch M, as by the kickdown operation of the accelerator pedal as will be presently described.

The rear end of the transmission case is closed by a pump housing structure comprising a housing member 91 and a rear cover 90 therefor. Within the member 91 the shaft 22 drives the usual speedometer gear 99 and has splined thereon a pump drive gear |00 meshed with the driven gear I0| secured to an outboard portion of a pump countershaft |02 journalled in members 91 and 99 and carrying the driving pump member |03. The gears |00, lili may be readily removed and other gears of different ratio substituted where variation in pumping pressures over the car speed range is desired.

Pump K draws its oil from the intake chamber |04 which is open to the tube 90 having its forward intake end disposed near the mid-length oi' the sump 89 so that when the car is travelling on a downgrade the inlet end of pipe 90 will still be below the level of the oil in the transmission case.

Oil under pressure, the pump K is delivered to gallery 92 and thence to motor H under control of a pilot valve N and a main valve O. This latter valve is slidably mounted in a boreY |00 of the transmission case and has a neck portion |06 connectlng the upper head portion |01 with the lntermediate head portion |09. These head portions slidably fit the bore |05 and define therewith the annular chamber or passage |09.

Below the head portion |08 the main valve O has another neck ||0 carrying at its lower end the abutment I I a spring I i2 operating between the ease and this abutment to bias the valve to its Fig. 12 position of venting motor H by opening passage 95 to the vent port II3 from which oil from the motor spills over to the sump 39. A second annular chamber or passage I I4 surrounds the neck l I0.

The abutment has a series of peripheral openings II! formed around its margin and seats in the Fig. 12 position on a base member ||9 at the annular upstanding flange I 'I thereof so that oil ln chamber H4 is free to iiow downwardly around neck ||0 then through openings IIB and beneath the face of abutment III. In this manner the oil in chamber Il when under pressure operates with a net upward force on valve O and causes the valve to move to its Fig. 13 position limited by the abutment |||5 striking the case shoulder H0.

The pilot valve N is formed with the head portions |I9, |20. and |2I slidable in a bore |22 of the valve housing |23. these head portions being connected by reduced neck portions |24 and |25 deilning the annular chambers or passages |20 and |21. Valve N is biased upwardly to its Fig. 13 position by a spring |20 and is moved downwardly to its Fig. 12 position by a solenoid P mounted above valve N on the housing |23.

Solenoid P comprises an armature |29 biased upwardly by a spring I3| which acts between the usual coil of solenoid P and a head |30 carried by armature |29. This armature has a reduced stem portion |32 which freely passed through an abutment ring |33 for engagement with the head portion ||9 of valve N s-uch that when the solenoid P is energized then the armature |29 moves downwardly from the Fig. 12 position to the Fig. 13 position causing the valve N to be lowered.

In the Fig. 13 position, upward bias of valve N by spring |28 is limited by engagement of head I|9 with the abutment ring |33, it being noted that the end of stem |32 is spaced above head ||9 by a short distance sulcient to cause the armature, when solenoid P. is energized, to gain momentum prior to engaging head ||9. This results in the armature imparting a hammer-like blow on the head I I9 and although this blow is of relatively small force it is sufficient to overcome any sticking tendency of the valve N as might be caused by cold weather making the oil sluggish or due to other causes.

The header 32 is in communication with branch passages |34, |35 opening respectively to chamber |09 and to chamber |26 under control of head I I9. Chamber I I4 communicates through a passage |38 with the port |31 which is always registered with chamber |26. A drain passage |30 leads from valve N back to the sump 99 and com- Il municateswithchamberllland,whenvalveN ismoveddownwardlyasinl'lg. 12,withthe chamberil. Afurtherdrainiorretmningoil i'romthcboreillbelowheadlli isprovided at illandiromthespaceaboveheadillbyavent lll. These venisimlreaninstanyoilaccumuloting below head lll and above head ill and rendersealingtheselieadsagaimt tomovethevalveagainstthellghtspringill.

BthesoIenoIdPisencrgiaedcausing move sumciently so that head lll Ill. Undertheseconirolnpassage Ill enters chamber lll where itis trappedbetweenheads iil and Illandhasno` movingeilectonvalve O. Therefore oil delivered on m winx;

III raises armature III and spring |28 raisesthepilotvalveNtothell'lgJapositionsol' 3u these Thiscausesheadiiltoopenpass f Ill and the oil from III. havlnganupwardiorceonvalveocausesthis valvetoquicklyraisetoitsrlg. l3position.

proportioned that head Ill Theoiipressureinchamberlll Il as otherwbe the 40 not complete its upward stroke. under pressure is supplied 2 and branch e Ill through III and Il to cylinder l! oi' motor H causing piston i3 to move forwardly on its power 45 stroke as aforesaid. Atthistime closed from drain ill as the head i2. clos ilifromdrain in.

It will be apparent that with the illustrated of the parts. This in turn simpliiles the control system and renders the same fool-prooi' in the assembly and use of the operating mechanism. It will be apparent that with the valving` parts positioned as illustrated in Fig. 13, at which time the pressure liuid is being supplied to the motor H for eiiecting clutching o! the sleeve D and for maintaining the same clutched. energization of the solenoid P will cause the pilot valve N to be restored to the Fig. 12 position. This immediately opens the e IH to the vent lil whereupon the spring H2 operates to move the main valve O from the Fig. i3 pomtion back to the Fig. l2 position. At this time the head ill oi' the main valve O blocks the upper end of bore I" serving to cut oi! the supply of pressure iluid from the gallery l! to the passage and opening this passage to the vent or reliei' port III whereupon the motor H is vented and the kickdown spring 8l comes into action for eiecting disengagement of sleeve D back to the Fig. 12 position, preferably accompanied by some form of torque unloading at the teeth o! sleeve D hereinaiter illustrated as a means for momentarily interrupting the ignition wstem of the engine A. When valve O moves downwardly from its Fig. i3 position the head ill covers the upper end oi' bore its prior to Opening the vent port Il# to the p II.

Referring now to Fig. 14, we have diagrammatically illustrated an electrical system for control of the transmission mechanism wherein the solenoid P is grounded at one end at Ill and has its other end extending by a conductor to a wire Il! under control however, oi a set of switch points Il! of a relay Q. A spring i biases the relay points so that they will open and the relay further includes the energizing solenoid Ill for controlling the relay points in conjunction with spring IM. In Fig. 14 it will be apparent that the solenoid ill is energized thereby serving to close the points i against the biasing action of the spring I".

The wire |42 extends through a fuse |48 to the wire Ill and thence through the ignition switch ill. ammeter I, to the usual storage battery Ill having a ground at IUI. The wire |42 from the battery extends to one end of the solenoid Il! and also by shunt connection through the points III, solenoid P, and thence to the ground lll. as aforesaid. I'he other end of the solenoid il! is adapted to be grounded at either o! two shunt paths leading to the grounds Ill and i, One o! these paths extends by wire Ill through an accelerator pedal controlled klckdown switch lli illustrated as a snap type of switch controlled by the snap-over operator ISI. The other shunt path extends by a wire lll through the aforesaid governor controlled switch M operated by the governor L which is driven as aforesaid at a speed proportionate to the travel of the motor vehicle by reason of the drive il. l! shown in Fig. 14.

The usual accelerator pedal lll is diagrammaticaliy illustrated as operating through the linkage IIB. IIB connected to the conventional engine throttle valve IUI the linkage also including a lever it! pivotally supported at |63 and being provided with the spaced nngers itl and it! ooerably associated with the switch operator Ill. In Fig. 14 the accelerator pedal is illustrated in its fuilv released position under the biasing action of spring i" causing the throttle valve ill to close and bringing the linger itl temwithinliberaltolerancesinthemanuiacture 16 lnpositiontomovetheswitchoperator ilttoa position for opening the kickdown switch |55. thereby breaking the shunt path through wire |54 to the ground |52. The arrangement is such that when the operator depresses the accelerator pedal |56 the throttle valve |6| is proportionately opened and as the accelerator pedal nears its wide open throttle position then the finger |64 will be brought to register with the switch operator |56 so that during the iinal throttle opening movement of the accelerator pedal, usually the last seven degrees of throttle opening movement, the switch |55 will be operated so as to snap over to its closed position thereby grounding the wire |54 at |52. Furthermore, once the kickdown switch has been closed in this manner, then it will remain in the closed position until the accelerator pedal has been fully released, it being apparent that during the last few degrees of iinal releasing movement of the accelerator pedal the nger |65 will be operated so as to effect the snap-over action of switch |55 to restore the same to the open position illustrated in Fig. 14.

Extending from the battery supplied current delivery wire |41 is a wire |51 leading to a conventional system of ignition R. for the engine A.

secondary coil |66, distributor and the various grounded spark plugs, one of which is illustrated at |1|. The primary coil |66 extends by a wire |12 to the usual breaker mechanism |16, means being provided to momentarily ground the ignition system through a grounding wire |14 connected to the primary coil and leading through the ignition controlling switch J for through the governor switch M or at |52 through the kickdown switch |55.

The system as illustrated in Fig. 14 illustrates the condition of the parts when the car is at a standstill with the engine operating under idling condition at which time the accelerator pedal |56 is released. the kickdown switch |55 is open, the governor switch M is closed. and the motor H is vented so that the sleeve D is in its rearward released position illustrated in Fig. l2 at which time the interrupter switch J is open. With the governor switch M closed, current from the battery |56 ilows through the wire |42. solenoid |45, governor switch M to the ground |56. With the relay solenoid energized relay points |43 are closed. Therefore, solenoid P is energized such that the pilot valve N will be in its Fig. 12 position opening the passage ||4 to the vent |66. Although the governor switch M is closed, it will be apparent that the ignition system R is not grounded at |53 because the interrupter switch J is open.

In driving the car forwardly the driver will depress the clutch pedal and manually manipulate the transmission C i'or either rst or third speeds or else reverse. Ordinarily vehicle starts are made by `shifting sleeve C forwardly to the high range for clutching with the teeth 45 and with the sleeve shifted in this manner and the clutch pedal 56 released, the car may be accelerated by depressing the accelerator pedal |56.

As the car is accelerated in third the critical speed of the governor L will be reached causing the governor switch M to open and eiecting 8 and 13 and the car may be accelerated in the third speed to any desired speed and this speed grounding either at 56 lil may be maintained by the driver as long as desired. the upshift from third to fourth speed being delayed until the driver releases the accelerator pedal |56 for the synchronous coast stepup of the sleeve D.

During the drive in third and when the governor L operates to open the governor switch M it will be apparent that this will de-energize the relay solenoid |45 whereupon relay spring |44 will operate to open the relay points |46. Upon opening o1' the points |46 solenoid P will be de-energized thereby eiiecting operation of the pilot valve N to the Fig. 13 position causing the oil delivered under pressure from pump K to move the main valve O from the Fig. 12 position to the Fig. 13 position and thus eiect delivery oi the oil pressure to the motor H for moving the piston 66 forwardly until it engages the stop 16. The sleeve D although biased forwardly by the engaging spring 1s will be brought to rest in the Figs. 8 and 13 drive block position where it will be held from ratcheting with the clutch teeth 24 until the driver releases the pedal |56 for the coast step-up engagement of the sleeve D to eil'ect drive in fourth. Although during the forward movement of piston 66 the cam 14 will operate to momentarily close the interrupter switch J, the ignition system R will not be grounded at |56 because during this forward stroke of the piston the governor switch M is open and thus the ignition grounding line is broken.

The downshii't from fourth to third may be effected by either oi' several controls. One of these controls responds to a full depression of the accelerator pedal |56 in bringing the throttle valve |6| to its fully opened position. thus eilecting a, closing operation of the kickdown switch |55. It is customary in devices of this sort to provide a yielding stop just prior to the last few degrees of throttle opening movement so that the driver does not accidentally eiect the kickdown operation that is required to overcome the force of the yielding stop, which is additional to the return spring |66, although the provision of the yielding stop is not necessary. When the kickdown switch |55 is closed it will be apparent that relay solenoid |45 will be energized thus closing the points |46 and thus eifecting energization of solenoid P, whereupon the pilot valve N will again be moved to the Fig. i2 position of venting the passageway 4 and causing the valve spring ||2 to restore the main valve 0 to the Fig. 12 position of venting the motor H.

1t will be apparent that when this kickdown operation is eiected the throttle |56 is substantially fully open so that the engine is delivering its torque through the teeth 24 and sleeve D, thus requiring some form of torque relief in order to facilitate rearward disengaging movement of sleeve D under the biasing action of the kickdown spring 64 and in the present illustration momentary interruption of the ignition system is employed for this purpose. In Fig. 14 the cams 14 and 15 are illustrated by broken lines to show the position of these cams when the piston 63 is in its fully forward position and at this time the sleeve D is engaged, there being the lostmotion gap 66 between the shoulder 66 of the rod 51 and the rear wall oi' piston 63 as illustrated in Fig. 13.

When the motor H is vented the sleeve D and head 63 will remain in their i'ully forward positions with head 83 engaging the member 12 because of the torque at the clutch teeth 24, but

a. predetermined the kickdown spring Il will immediately operate the piston rearwardly sulciently to take up the gap ll, this motion being sumcient to cause the cam 1i to close the interruptor switch J thus grounding the ignition-system R at |52 through the previously closed klckdown switch |55. With thus interrupted the torque is rethe kickdown spring 8l the piston 63, rod B1, and as a unit back to the Fig. 12 these parts, to allow the interrupter switch J to open as the sleeve D leaves the teeth 24 thus quickly restoring the ignition system R to its normal operation. Y The accelerator pedal being depressed will cause the drive shaft 2| to speed up and effect operation of the third speed by automatic clutching of the overrunning clutch F and the car may then be driven in third speed until the upshift is again desired and is obtained at any time, that the speed of the car does not slow down sumciently to cause the governor swish M to close, by releasing the accelerator pedal i to open the kiekdown switch |65 and effect de of solenoid P with resulting supply of pressure fluid to the motor H for the coast step-up t of sleeve D with the teeth 2l.

The other of the aforementioned controls for effecting the from fourth to third comprises the governor control system for automatically directing a downshift when the car reaches relatively low speed, as for example in bringing the car to rest. This control system operates to close the governor switch M resulting in providing a ground for the relay solenoid Il! so as to eifect the downshift in the same manner as aforesaid by closing operation of the kickdown switch ill, it being apparent that this downshift will be effected accompanied by momentary interru on of the ignition system lust as in the case of the accelerator kickdown. Thus on bringing the car to rest. as when stopping for a trame light, it is not necessary for the driver to man pulate any of the transmission controls or the clutch pedal 50, the fluid coupling atB Hm ting idling of the engine with the car at rest. When it is desired to again accelerate the vehicle, then the aforesaid cycle of operations for time upshift from third to fourth is repeated.

It will be apparent that the mechanism opcrates for step-up and step-down between nrst and second speeds in the same manner as aforesaid in connection with shifts between third and fourth. It is, of course, necessary for the driver to manipulate the ion into the low range by effecting rearward shift of sleeve G to clutch with the teeth l in order to initially accelerate the car in first. the step-up to second being obtained when the car is driven above the critical speed of L and the accelerator pedal lil is subsequently released for the synchronous coast step-up from rst to second. when driving in second the nrst speed may be restored by either a full depression of the accelerator pedal lll for the kickdown operation orbybringingthecartorestorslowing thesame down sufciently to effect closing of the governor switch H Jimi; as aforesaid.

Itisforthecartobeinitiallyaccelerated in first followed by a coast step-up to second and then when the sleeve G is shifted forwardly fourth will be obtained. skipping third. 0n the other hand if the car is accelerated in Y ernor switch M opens the first and the sleeve G is shifted forwardly prior to the coast step-up. then third will be obtained by skipping second. and when the accelerator pedal is released for the coast step-up above the critical governor speed the fourth or direct speed will be brought into action.

The saine general system responds in coast step-up and kickdown and driving in reverse which is effected by a rearward shift of the idler 4| into mesh with the gear 43. When the car is driven in this low reverse startingspeed, accelerator pedal Il! may be fully released for a coast synchronous step-up by forward shift of sleeve D and the low reverse may be restored by bringing the car to rest or by kickdown operation of the accelerator pedal, the general system operating just as aforesaid.

It will furthermore be apparent that the system will operate to drive the engine A in order to start the same as when the battery l is deficient. Under such conditions the driver may shift the sleeve G to either the low or high range and when the car is pushed the pump K will develop suicient pressure so that when the govmotor H will be energized to effect engagement this operation may be somewhat facilitated by momentary operation of the clutch pedal iii in instances where the blocker E may tend to block the sleeve against engagement.

In the event that the governor direct an upshift of L operates to the transmission C at a time when the driving shaft 2| is rotating at a speed less than that of the sleeve D, motor H will be energized to bias the sleeve D forwardly through the engaging spring 19 as aforesaid, but under such conditions the sleeve D will be blocked by the blocker E in the Fig. ll coast blocking position of the parts. This condition is experienced when, for example with the transmission set for one of the forward driving speeds of first or third, the car is accelerated by action of gravity down a hill with the engine continuing to idle as accommodated by the overrunning clutch l".

. up the As the car increases in speed the governor L will open the governor switch M and effect pressure fluid operation of the motor H and the sleeve D will be brought into the coast block condition of Fig. l1. If now the accelerator pedal lil is depressed the engine driving shaft 2| will be speeded up to a speed equal to that of the sleeve D and higher than this speed sufficiently to pick drive in first or third by engagement of the overrunning clutch F. Under such conditions the sleeve D will not be unblocked even though the speed of shaft 2| passes through the synchronous sleeve relationship with respect to the sleeve D, and the sleeve D will then be established in the drive block position of Fig. 8, as previously set forth in connection with the description of the sleeve and blocker relationships illustrated in Figs. 'l and ll. Clutching engagement of the sleeve D is then effected in response to a release of the accelerator pedal at the time when the engine slows down the driving shaft 1| to a condition of synchronous relationship with respect to rotation of sleeve D, thereby effecting the coast step-up from first or third to either second or fourth depending on whether the man ualiy adjustable sleeve G is positioned in its rearward low range setting or forwardly in its high range setting.

Referring to Fig. l5, we have illustrated a modified arrangement of controlling the ignition interruption wherein the ignition grounding of the sleeve D and 11 linenowincludesasecondsetofrclaypoints |1l tied to the aforesaid points |43 and opening and closing therewith as aforesaid. The grounding line |14 furthermore differs from the Fig. 14 arrangement in that it is grounded at |16 beyond the ignition control switch J. With this arrangement the aforesaid gap I8 is no longer necessary but may still be employed if desired and the reduced portion 13 may now be lled in as illustrated by the skirt I4 of the piston I3' in Fig. l5 which piston is otherwise similar to piston el. Otherwise the Fig. arrangement is identical with that aforesaid, only a portion of the aforesaid embodiment including the control diagram of Fig. 14 being illustrated in Fig. l5 to avoid unnecessary duplication.

With the Fig. l5 arrangement the system operates identically as that aforesaid with the following exceptions. When the motor H is energized by pressure iiuid supply thereto, piston ll' is projected forwardly so that switch J closes and then maintains switch J closed during the balance of the forward stroke of the piston. The ignition system is not grounded out however because at such time the governor switch M is open, thus de-energizing solenoid coil |45 and allowing relay spring |44 to simultaneously open both sets of points |43 and |15. Thus with points |15 open the grounding line |14 is broken.

When a downshift is called for. at the time when sleeve D is clutched, either by closing the kickdown switch |55 or by the closing of governor switch M, then relay solenoil |45 is energized causing points |43 and |15 to close. The effect of closing points |43 is ,lust as aforesaid in that this energizes the solenoid P to vent the motor H. At the same time closing of points |15 now of itself completes the grounding circuit of line |14 to ground |16 because switch J is already closed at this time. Thus ignition interruption is not dependent on initial movement of some part to close the switch J, as is necessary in Fig. 13 in connection with gap Il. and the sleeve D is disengaged by movement of piston 63' rearwardly by the spring I4 operating to shift rod 61 rearwardly. The ignition is restored as soon as the cam 14 moves rearwardly of the ball operator 11 and this cam may be located at any desired point for timing the ignition restoring with the sleeve disengaging travel. The Fig. 15 system otherwise operates as set forth for Fig. 14.

In Fig. 16, we have illustrated a slightly modiiied piston construction for use instead of piston 63 of Fig. 14 and instead of piston 61' of Fig. l5 by lling in the recess 1I. In Fig. 16 the piston ll* has an annular groove |11 opening outwardly of the outer skirt I5 and receiving the annular rubber-like yielding sealing ring |18 having an outer cylindrical face in sliding sealing engagement with the cylinder Il. The groove |11 is open by a passage |19 to the pressure fluid space behindmthe piston and communicating with pressure fluid supply passage Il. Ring |18 is substantially U-shaped in section whereby the pressure uid operates to seat the legs |80 of the ring |18 on the walls of the groove |18, the pressure fluid also operating to expand the ring outwardly into sealing contact with the cylinder. In this manner an eilicient seal is provided to insure against fluid leakage forwardly around the piston especially where the selected size of pump K and the drive ratio therefor is such that it is desired to minimize fluid leakage. Usually the pump capacity is such that iiuid leakage is not criticalthusmakingitunnccsssarytoprovidea seal of the pressure duid expanded type.

We claim:

i. In a power transmission for a motor vehicle having an engine, a driving shaft adapted to receive drive from the engine. a driven shaft adapted to drive the vehicle, relatively slow speed driving means for driving the driven shaft from the driving shaft at a predetermined speed ratio. relatively fast speed driving means for driving the driven shaft from the driving shaft at a predetermined speed ratio dii'lerent from that aforesaid and at a speed greater than that of said slow speed driving means and including positively in.

terengaging drive control elements one of which is movable relative to the other, said drive control elements being adapted, when interengaged. to establish said fast speed drive, said relatively slow speed driving means including control means operating automatically to effect operation of this drive in response to release of said relatively fast speed driving means and acceleration of the driving shaft, a iiuid pressure motor comprising a pressure chamber and a pressure responsive member operable therein in response to delivery of fluid under pressure to said pressure chamber, means operably connecting said pressure responsive member with said movable drive control element for biasing this control element into said interengaging relationship with the other of said drive control elements in response to iluid pressure operation of said pressure responsive member, biasing means operable, when said pressure chamber is vented, to bias said movable control element into disengaged relationship with respect to the other of said drive control elements, a pump for delivering fluid under pressure from a source of iluid supply to said pressure chamber, means for driving said pump at a speed proportional to the speed of the vehicle, means for controlling said delivery of pressure duid to said pressure chamber and venting said chamber comprising, a pilot valve of relatively small inertia movable over a relatively small stroke between two positions. ported guide means for slidably guiding said pilot valve during movement thereof, said ported guide means and said pilot valve together presenting passage means for the pressure fluid so constructed and arranged as to balance said pilot valve against tendency toward displacementv thereof by the pressure fluid in all positions of movement of said pilot valve. a main valve of relatively large inertia movable over a relatively large stroke between two positions and having a portion so arranged as to be acted on by the pressure fluid to produce a force acting to move said main valve to one of its said positions, a spring biasingsaid pilot valve to one of its said positions, solenoid operating means for moving said pilot valve to the other of its said positions. a spring biasing said main valve to the other of its said positions, means responsive to movement of said pilotvalve by its said spring biasing means when said solenoid is de-energized for subjecting pressure iiuid delivered by the pump to said portion of said main valve thereby to eilect pressure fluid movement of said main valve to its said one position in opposition to said spring bias thereon, means responsive to said pressure fluid induced movement of said main valve for effecting communication between the pressure iiuid delivered by the pump and said pressure chamber whereby to effect said pressure iiuid operation of said pressure responsive member, means for controlling energization of said solenoid in response lto the speed of the vehicle. means responsive to enersiaation of said solenoid to effect return movement of said pilot valve to its said other position for venting said main valve so as to relieve the same from the movement inducing action of the pressure duid thereby to edect return movement of said main valve by the action of said spring bias thereon, and means responsive to said return movement of said main valve for venting said pressure chamber.

2. In a power transmission for a motor vehicle having an engine, a driving shaft adapted to receive drive from the engine. a driven shaft adapted to drive the vehicle, relatively slow speed driving means for driving the driven shaft from the driving shaft at a predetermined speed ratio, relatively fast speed driving means for driving the driven shaft from the driving shaft at a predetermined speed ratio different from that aforesaid and at a speed greater than that of said slow speed driving means and including positively interengaging drive control elements one of which is movable relative to the other, said drive control elements being adapted, when interengaged. to establish said fast speed drive, said relatively slow speed drivingmeans includlng control means operating automatically to effect operation of this drive in response to release of said relatively fast speed driving means and acceleration of the driving shaft. a fluid pressure motor comprising a pressure chamber and a pressure responsive member operable therein in response to delivery of duid under pressure to said pressure chamber, means operably connecting said pressure responsive member with said movable drive control element for biasing this control element into said interengaglng relationship with the other of said drive control elements in response to duid pressure operation of 'said pressure responsive member, biasing means operable, when said pressure chamber is vented, to bias said movable control element into disengaged relationship with respect to the other of said drive control elements, a pump for delivering duid under pressure from a source of duid supply to said pressure chamber, means for driving said pump at a speed proportional to the speed of the vehicle, means for controlling said delivery of pressure duid to said pressure chamber and venting said chamber comprising, a pilot valve movable between two psitions, ported guide means for slldably guiding said pilot valve during movement thereof, said ported guide means and said pilot valve together presenting passage means for the pressure duid so constructed and arranged as to balance said pilot valve against tendency toward displacement thereof by the pressure duid in all positions of movement of said pilot valve, a main valve movable between two positionsiand having a p0rtion so arranged as to be acted on by the pressure duid to produce a. force acting to move said main valve to one of its said positions, a spring biasing said pilot valve to one of its said positions, solenoid operating means for moving said pilot valve to the other of its said positions, a spring biasing said main valve to the other of its said positions, means responsive to movement of said pilot valve to its said other position for subjecting pressure duid delivered by the pump to said portion of said main valve thereby to edect pressure duid movement of said main valve to its said one p0- sltion in opposition to said springbias thereon, means responsive to said pressure duid induced movement of said main valve for ed'ecting communication between the pressure duid delivered bythe pumpandsaidpressurechamberwhereby to edect said preure duid operation of said pressure responsive member, means for so controlling eneraisation of said solenoid as a func tion oi'speed oithevehicleastoed'ectenergiaation of said solenoid when the vehicle is brought to rest and de-tion of said solenoid when the vehicle, on accelerating the same from rest by operation of said relatively slow speed driving means, reaches a predetermined speed, means responsive to return movement of said pilot valve for venting said main valve so as to relieve the same from the movement inducing action of the pressure duid thereby to effect return t of said main valve by the action of said spring bias thereon. and means responsive to said retum movement of said main valve for venting said pressure chamber.

3. In a power t for a motor vehicle having an engine equipped with an ignition wstem. a driving shaft adapted to receive drive from the engine, a driven shaft adapted to drive the vehicle, relatively slow speed driving means for driving the driven shaft from the driving shaft at a predetermined-speed ratio, relatively fast speed driving means for driving the driven shaft from the driving shaft at a predetermined speed ratio diderent from that aforesaid and at a speed greater than that of said slow speed driving means and including positively in drive control elements one of which is movable relative to the other, said drive control elements being adapted, when interengaged. to establish said fast speed drive, said relatively slow speed driving means including control means operating automatically to eil'ect operation of this drive in response to release of said relatively fast speed driving means and acceleration of the driving shaft, a duid pressure motor comprising a pressure chamber and a pressure responsive member operable therein in response to delivery of duid under pressure to said pressure chamber, means operably connecting said pressure ve member with said movable drive control element for biasing this control element into said interengaging relationship with the othin' of said drive control elements in response to duid preasure operation of said pressure ve member, biasing means operable, when said pressure chamber is vented, to bias said movable control element into disengaged relationship with respect to the other of said drive control element, a pump for` delivering duid under pressure from a source of duid supply to saidpressure chamber, means for driving said pump at a speed proportional to the speed of the vehicle, means for controlling said delivery of pressure duid to said pressure chamber and venting said chamber comprising, a pilot valve of relatively small inertia movable over a relatively small strobe between two positions, ported guide means for slidably guiding said pilot val during Inovenient thereof, said ported guide means and pid pilot valve together presenting y msnm for the pressure duid so constructed and arranged as to balance said pilot valve against tendency toward displacement thereof by the pressure duid in all positions of movement of said pilot valve. a main valve of a relatively large inertia movable over a relatively large strobe between two positions and having a portion soarrangedastobeactedonbythepreasure duid to produce aforce acting tomovesald main valve to one of its said positions. a sll'ing biasing said pilot valve to one ot the said positions, solenoid means having an armature provided with a pilot valve operating portion so spaced from said pilot valve, when the latter is in its said one position. that movement of said armature portion will strike the pilot valve as an incident to moving said pilot valve to the other of its said positions, a spring biasing said main valve to the other of its said positions, means responsive to movement of said pilot valve by its said spring biasing means when said solenoid is de-energized for subjecting pressure fluid delivered by the pump to said portion of said main valve thereby to effect pressure fluid movement of said main valve to its said one position in opposition to said spring bias thereon, means resposive to said pressure iiuid induced movement of said main valve for effecting communication between the pressure fluid delivered by the pump and said pressure chamber whereby to effect said pressure duid operation of said pressure responsive members means responsive to energization of said solenoid to effect return movement of said pilot valve to its said other position for venting said main valve so as to relieve the same from the movement inducing action of the pressure fluid thereby to effect return movement of said main valve by the action of said spring bias thereon, means responsive to said return movement of said main valve for venting said pressure chamber, means operable to effect momentary interruption of the engine ignition system thereby to facilitate movement of said movable drive control element into its said disengaged relationship as aforesaid, said interruption means including an ignition controlling switch and means for effecting operation thereof in response to movement of said pressure responsive member.

4. In a power transmission for a motor vehicle having an engine, a driving shaft adapted to receive drive from the engine, a driven shaft adapted to drive the vehicle, relatively slow speed driving means for driving the driven shaft from the driving shaft at a predetermined speed ratio, relatively fast speed driving means for driving the driven shaft from the driving shaft at a predetermined 4speed ratio diil'erent from that aforesaid and at a speed greater than that of said slow speed driving means and including positively interengaging drive control elements one of which is movable relative to the other, said drive control elements being adapted, when interengaged, to establish said fast speed drive, said relatively slow speed driving means including control means operating automatically to effect operation of this drive in response to release of said relatively fast speed driving means and acceleration of the driving shaft, a fluid pressure motor comprising a pressure chamber and a pressure responsive member operable therein in response to delivery of fluid under pressure to said pressure chamber, means operably connecting said pressure responsive member with said movable drive control element for biasing this control element into said interengaging relationship with the n other of said drive control elements in response to Aiiuid pressure operation of said pressure responsive member, biasing means operable, when said pressure chamber is vented. to bias said movable control element into disengaged relationship with respect to the other of said drive control elements, a pump for delivering fluid under pressure from a source of uid supply to said pressure tor controlling said delivery of pressure iiuid to said pressure chamber and venting said chamber comprising, a pilot valve of relatively small inertia movable over a relatively small stroke between two positions, a main valve of relatively large inertia movable over a relatively large 4stroke between two positions and having a portion so arranged as to be acted on by the pressure fluid to produce a force acting to move said main valve to one ot its said positions. a spring biasing said pilot valve to one of its said positions. solenoid operating means for moving said pilot valve to the other of its said positions. a spring biasing said main valve to the other of its said positions, means i'or supporting and guiding said valves for movement as aforesaid in side by side relationship adjacent each other, means providing a valve-controlling pressure fluid conducting passage adapted, under control of said pilot valve, to deliver pressure fluid from said pump and said pilot ,valve to said main valve portion, means providing a vent for said valve-controlling passage so arranged as to be selectively opened and closed under control oi' said pilot valve when moved between its aforesaid .positions and, when so closed in response to movement of said pilot valve from one of its said positions to the other, to subject said main valve portion to pressure uid delivered thereto through said valve-controlling passage thereby to effect said pressure fluid movement to said main valve in opposition to said spring bias thereon, means responsive to said pressure iluid induced movement of said main valve for eilecting communication between the pressure fluid delivered by the pump and said pressure chamber whereby to effect said pressure fluid operation of said pressure responsive member, means for controlling energization of said solenoid in response to the speed of the vehicle, means responsive to return movement of said pilot valve for opening the vent of said valvecontrolling passage` thereby to relieve said main valve portion from the movement inducing action o! the pressure iluid thereby to effect return movement of said main valve by the action of said spring bias thereon, andmeans responsive to said return movement of said main valve for venting said pressure chamber.

5. In a power transmission for a motor vehicle having an engine equipped with an accelerator controlled throttle, a driving shaft adapted to receive drive from the engine. a driven shaft adapted to drive the vehicle, relatively slow speed drivingmeans for driving the driven shaft from the driving shaft at a predetermined speed ratio, relatively fast speed driving means for driving the driven shaft from the driving shaft at a predetermined speed ratio dierent from that aforesaid and at a speed greater than that of said slow speed driving means and including positively interengaging drive control elements one of which is movable relative to the other, said drive control elements being adapted, when interengaged, to establish said fast speed drive, said relatively slow speed driving means including control means operating automatically to ellect operation of this drive in response to release of said relatively fast speed driving means and acceleration of the driving shaft, a uid pressure motor comprising a pressure chamber and a pressure responsive member operable therein in response to delivery of fluid under pressure to said pressure chamber, means operably connecting said pressure responsive member with said movable drive control elechamber, means for driving said pump, means Il ment for biasing this control element into said 23 interengeginlreiationshipwiththeotheroi'said drive controlelementsinresponsetotlnidpressure operation of said pressure member, biasing means operable, when said pressure chamber is vented, to bias said movable control element into disengaged relationship with respect to the other o1 said drive control elements, a

pump for delivering fluid under pressure from a 'thereof by the pressure fluid in all positions o! movement of said pilot valve, a main valve oi' relatively large inertia movable over a relatively large stroke between two positions and having a portionsoarrangedastobeactedonbytltepres.

sure fluid to produce a force acting to move said main valve to one of its said positions, a spring biasing said pilot valve to one o! its said positions, solenoid operating meam for moving said pilot valve tothe other of its said positions, a spring biasing said main valve to the other o! its said positions, means responsive to movement oi' said pilot valve by its said spring biasing Vmeans when said solenoid is de-energized for subjecting pressure iiuid delivered by the pump to said portion of said main valve thereby to eiiect pressure fluid movement of said main valve to its said one position in opposition to said spring bias thereon, means responsive to said pressure iiuid induced movement of said main valve lor effecting communication between the pressure duid delivered by the pump and said pressure chamber whereby to eil'ect said pressure uid operation of said pressure responsive member, means for controlling energization of said solenoid in response to driver operation of said accelerator in throttle opening direction, means responsive to tion of said solenoid to eifect return movement of said pilot valve to its said other position for venting said main valve so as to relieve the same irom the movement inducing action of the pressure iiuld thereby to effect return movement of said main valve by the action of said spring bias thereon. and means responsive to said return movement o! said main valve for venting said pressure chamber.

6. In a power transmission for an automotive vehicle having an engine of the type provided with an ignition system and an accelerator controlled throttle, a driving shalt adapted to re. ceive drive from the engine, a driven shaft adapted to drive the vehicle, relatively slow speed driving means for driving the driven shaft from the driving shaft at a predetermined speed ratio, relatively fast speed driving means i'or driving the driven shaft from the driving shaft at a pre. determined speed ratio diierent from that aforesaid and at a speed greater than that of said slow speed driving means and including positively interengaging drive control elements one oi which is movable relative to the other, said drive control elements being adapted. when inte, to establish said fast speed drive, said relatively slow speed driving means including control means operating automatically to eneet operation ot this drive in response to release o! said iastspeeddrivingmeansand aecelerationoithe driving shaft. a iluid pressure motor comprising a pressure chamber and a pressure responsive g member operable therein in response to delivery oi' iiuid under pressure to said pressure chamber. means operably connecting said premura responsive member with said movable drive controleiement for biasing this control element into laid interengaging relationship with the other oi' said drive control elements in response to iiuid pressure operation of said pressure responsive member. -biasing means operable, when said pressure ohamberisventemtobiassaidmovableeontrol element into disengaged relationship with respect to the other of said drive control element, a pump lor delivering iiuid under pressure from a source ot nuid supply to said pressure chamber. means for driving said pump, means for connoilingsaiddeliveryofpressureiluidtosaid chamber and venting said chamber comprising, a pilot valve of relatively small inertia movable over a relatively short stroke between two positions, a main valve oi relatively large inertia movable over a relatively long stroke between two positionsandhavingaportionsoarrangedesto beactedonbythepressureiimdtoprodueeaforce aetingtomovesaidmalnvalvetooneoiitssaid positions, a spring biasing said pilot valve to one of its said positions, solenoid means having an armature provided with a pilot valve operating portion so spaced from said pilot valve, when the latter is in its said one position. that movement o! said amature portion will strike the pilot valve as an incident to moving said pilot valve to the other of its said positions, a spring biasing said main valve to the other of its said positions, meansfor supporting and guiding said valves for movement as aforesaid in side-by-side relationship adjacent each other. means responsive to movement of said pilot valve by its said spring biasing means when said solenoid is de-energlaed for subjecting pressure iluid delivered by the pump to said portions of said main valve thereby to efiect pressure fluid movement of said main valve to its said one position in opposition to said spring bias thereon, means responsive to said pressure uid induced movement of said main valve ior eilecting communication between the 50 pressure uid delivered by the pump and said pressure chamber whereby to eilect said pressure fluid operation oi' said pressure responsive member. means for controlling energization of said solenoid in response to driver operation o! said 55 accelerator in throttle opening direction, means 'responsive to energization of said solenoid to e1'- iect return movement of said pilot valve to its said other position for venting said main valve so as to relieve the same from the mt ingo ducing action of the pressure fluid thereby to effeet return movement of said main valve by the action of said spring bias thereon, and means responsive to said returnV movement of said main valve for venting said pressure chamber, means as 'operable to eileet momentary interruption oi the engine ignition system thereby to facilitate movement of said movable drive control element into iis said disengaged relationship as aforesaid. said `interruption means including an ignition control- 'm ling switch and means for effecting operation thereof in respome to movement of said pressure responsive member.

7. In a power for a motor vehicle havinganenglne,adrlvingshaftadaptedtore lraceivedrivefrorntheenginaadrlvenahatt adapted to drive the vehicle, change speed means operabiy disposed between said shafts for edecting step-up and step-down variation in the speed ratio drive through the transmission, a pressure fluid operated motor for controlling said change speed means. a pump operable to deliver fluid under pressure to said motor. valving means for so controlling said delivery of pressure fluid to said motor as to selectively eii'ect iiuid operation of and venting of said motor, said valving means comprising a relatively long stroke large mass main valve and a relatively short stroke small mass pilot valve. a spring opposed solenoid adapted, when energized, to effect an operation of said pilot valve, ported guide means for slidably guiding said pilot valve during movement thereof, said ported guide means and said pilot valve together presenting passage means for the pressure iiuid so constructed and arranged as to balance said pilot valve against'tendency toward displacement thereoi' by the pressure fluid in all positions of movement of said pilot valve, and means responsive to spring operation of said pilot valve, when said solenoid is de-energized, for causing pressure fluid delivered by said pump to act on said main valve to effect pressure fluid operation of said main valve.

8. In a power transmission for a motor vehicle having an engine, a driving shaft adapted to receive drive from the engine, a 4driven shaft adapted to drive the vehicle, change speed means operably disposed between said shafts for eifecting step-up and step-down variation in the speed ratio drive through the transmission, a pressure duid operated motor for controlling said change speed means, a pump operable to deliver fluid un der pressure to said motor, valving means for so controlling said delivery of pressure fluid to said motor. as to selectively effect fluid operation of and venting of said motor, said valving means comprising a pilot valve adapted for reciprocation between limits defining a relatively short stroke movement and a main valve adapted for reciprocation between limits defining a relatively long stroke movement, a spring opposed solenoid adapted, when energized, to eil'ect an operation of said pilot valve, ported guide means for slidably guiding said pilot valve during movement thereof, said ported guide means and said pilot valve together presenting passage means for the pressure fluid so constructed and arranged as to balance said -pilot valve against tendency toward displacement thereof by the pressure fluid in all positions of movement of said pilot valve. and means responsive to spring operation of said pilot valve, when said solenoid is de-energized, for causing pressure fluid delivered by said pump to act on said main valve to eil'ect pressure fluid operation of said main valve.

9. In a power transmission for a motor vehicle having an engine, a driving shaft adapted to receive drive from the engine, a driven shaft adapted to drive the vehicle, change speed means operably disposed between said shafts for effecting step-up and step-down variation in the speed ratio drive through the transmission, a pressure fluid operated motor for controlling said change speed means, a pump operable to deliver uid under pressure to said motor. valving means for so controlling said delivery of pressure fluid to said motor as to selectively effect fluid operation of and venting of said motor, said valving means comprising a pilot valve of relatively small mass adapted for reciprocation between limits defining a relatively short stroke movement and a main 26 valve of relatively large mass adapted for reciprocation between limits denning a relatively long stroke movement. ported guide means for slidably guiding said pilot valve during movement thereoi', said ported guide means and said pilot valve together presenting passage means for the pressure fluid so constructed and arranged as to bal ance said pilot valve against tendency toward displacement thereof by the pressure fluid in all positions of movement oi said pilot valve, means for reciprocating said pilot valve as aforesaid including spring opposed solenoid operating means for actuating said pilot valve in at least one direction of, and between its said limits of, its reciprocatory movement aforesaid, means responsive to spring operation of said pilot valve from one of its limits of movement to the other, when said solenoid is de-energized for causing pressure huid delivered by said pump to act on said main valve to effect pressure fluid operation of said main valve in at least one direction of, and between its said limits of, its reciprocatory movement aforesaid thereby to effect said step-up, torque unloading means for said change speed means operable to facilitate said step-down, and

means operable in response to operation of said motor when vented and in part responsive to predetermined retardation oi' the speed of travel of said vehicle for effecting energization of said solenoid and a momentary operation of said torque unloading means.

l0. In a power transmission for a motor vehicle having an engine, a driving shaft adapted to receive drive from the engine, a driven shaft adapted to drive the vehicle, change speed means operably disposed between said shafts for effecting step-up and step-down variation in the speed ratio drive through the transmission, a pressure iiuid operated motor for controlling said change speed means, a pump operable to deliver fluid under pressure to said motor, valving means for so controlling said delivery of pressure uid to said motor as to selectively effect fluid operation of and venting of said motor, said valving means comprising a relatively large mass long stroke main valve and a relatively small mass short stroke pilot valve, ported guide means for slidably guiding said pilot valve during operation thereof, said ported guide means and said pilot valve together presenting passage means for the pressure fluid so constructed and arranged as to balance said pilot valve against tendency toward displacement thereof by the pressure fluid in all positions of operation of said pilot valve, solenoid operating means for eii'ecting an operation of said pilot valve, spring means for effecting a return opera tion of said pilot valve, and means responsive to spring operation of said pilot valve, when said solenoid is de-energized for effecting pressure fluid operation of said main valve.

11. In a power transmission for a motor vehicle having an engine, a driving shaft adapted to receive drive from the engine, a driven shaft adapted to drive the vehicle, change speed means operably disposed between said shafts for eifecting step-up and step-down variation in the speed ratio drive through the transmission, a pressure fluid operated motor for controlling said change speed means, a pump operable to deliver fiuid under pressure to said motor, valving means for so controlling said delivery of pressure fluid to said motor as to selectively effect fluid operation of and venting of said motor, said valving means comprising a main valve and a pilot valve, solenoid means having an armature provided with a pilot desde valve operating portion so spaced from said pilot valve, when the latter is in one position o! its operation, that movement of said armature portion will impart to the pilot valve a hammerlike blow as an incident to moving said pilot valve to another position of its operation, and means responsive to operation of said pilot valve between its said positions for edecting pressure duid induced movement of said main valve.

12. In a power transmission for a motor vehicle having an engine equipped with an accelerator controlled throttle and an ignition system, a driving shaft adapted to receive drive from the engine, a driven shaft adapted to drive the vehicle, change speed means operably disposed between said shafts for effecting step-up and step-down variation in the speed ratio drive through the transmission, a pressure duid operated motor for controlling said change speed means, a pump operable to deliver duid under pressure to said motor, valving means for so controlling said delivery of pressure duid to said motor as to selectively eil'ect duid operation of and venting of said motor, said vaiving means comprising a relatively large inertia long stroke main valve and a relatively small inertia short stroke pildt valve, ported guide means for slidably 'guiding said piot valve during movement thereof, said ported guide means and said pilot valve together presenting passage means for the pressure duid so constructed and arranged as to balance said pilotvalve against tendency toward displacement thereof by the pressure duid in all positions of movement of said pilot valve, means for effecting operation of said pilot valve comprising spring opposed solenoid means having an amature provided with a pilot valve operating portion so spaced from said pilot valve, when the latter is in its said one position, that movement oi said armature portion will strike the pilot valve as an incident to moving said pilot valve. means responsive to spring operation of said pilot valve, when said solenoid is de-energized for causing pressure duid delivered by said pump to act on said main valve to edect pressure fluid operation of said main valve, means including an ignition controlling switch operably responsive to operation of said motor for effecting momentary interruption of the operation of said ignition system thereby to facilitate step-down change in said change speed means, and means responsive to driver operation of said accelerator in throttle opening direction for eilecting energization of said solenoid.

13. In a power transmission for a motor vehicle having an engine equipped with an accelerator controlled throttle and an ignition system, a driving shaft adapted to receive drive from the engine, a driven shaft adapted to drive the vehicle, change speed means operably disposed between said shafts for effecting step-up and stepdown variation in the speed ratio drive through the transmission. a pressure duid operated motor for controlling said change speed means, a pump operable to deliver duid under pressure to said motor, valving means for so controlling said delivery of pressure duid to said motor as to selectively effect fluid operation of and venting of said motor, said valving means comprising a relatively high inertia long stroke main valve and a relatively low inertia short stroke pilot valve, ported guide means for slidably guiding said pilot valve during movement thereof, said ported guide means and said pilot valve together presenting passage means for the pressure duid so constructed and arranged as to balance said pilot 28 valve against tendency toward displacement thereof by the pressure duid in all positions of movement of said pilot valve, means for eil'ecting operation of said pilot valve comprising spring opposed solenoid means having an armature provided with a pilot valve operating portion so spaced from said pilot valve, when the latter is in its said one position, that movement of said armature portion will strike the pilot valve as an incident to moving said pilot valve, means responsive to spring operation of said pilot valve, when said solenoid is deenergized for causing pressure duid delivered by said pump to act on said main valve to effect pressure duid operation of said main valve, means responsive to the vehicle attaining a predetermined speed for ed'ecting de-energization of said solenoid to cause pressure duid operation of said motor, and means responsive to driver operation o! said accelerator, when the vehicle speed is above that aforesaid, for ed'ecting energization of said solenoid to cause venting of said motor.

14. In a power ton ior a motor vehicle oi' the type comprising change speed means for effecting step-up and step-down variation in the speed ratio drive through the on, a pressure duid operated motor for controlling said change speed means, said motor comprising a casing structure formed with a cylinder providing a pressure duid chamber, means carried by said casing structure provided with a guideway coaxial with said cylinder, a piston having a skirted portion slidably engaging the walls of said cylinder and adapted for pressure fluid indud movement, a rod in thrust receiving relationship with said piston and having an end portion slidably supported in said guideway, said change speed means comprising an element shiftable for controlling said variation in the transmission speed ratio drive, a relatively small force compression spring having one end thereof extending within the skirted portion of said piston for seating on said piston, the other end of said spring being disposed for transmitting thrust to said shiftable element whereby to move said element in one direction in response to pressure duid operation of said piston, an abutment member carried within said cylinder, and a relatively large force compression spring coaxially surrounding said small force spring and extending between said abutment and said piston whereby to bias the piston for return movement when said motor is vented.

i5. In a power transmission for a motor vehicle having an engine equipped with an accelerator controlled throttle and an ignition system, a driving shaft adapted to receive drive from the engine, a driven shaft adapted to drive the vehicle, change speed means for effecting step-up and step-down variation in the speed ratio drive through the traon, a pressure duid operated motor for controlling said change speed means, a pump operable to deliver duid under pressure to said motor. valving means for so controlling said delivery of pressure duid to said motor as to selectively effect duid operation of and venting of said motor, a solenoid for controlling said valving means, an ignition controlling switch operably connected to the power element of said motor, a vehicle speed responsive switch, an accelerator controlled switch, a source of electrical energy, relay means comprising two sets of points connected so as to together open and close and a relay-solenoid for controlling opening and closing oi said sets of points, circuit forming means lead- 

